Improvement in door-sheaves



UNiTED STATES PermitirV OFFICE..

ROBERT G. HATFIELD, OF NEW YORK, N. Y.

IMPROVEMENT IN DOOR-SH EAVES.

Spccilication forming part of Letters Patent No. L13,205, dated June 2l,1864.

To @ZZ whom it may concern:

Be it known that I, VROBERT G. HATEIELD, of the city of New York, in thecounty and State of New York, have invented anew and ImprovedSlidingDoor Roller-Sheave; and I do hereby declare that the following isa full and exact description thereof, reference being had to theaccompanying drawings, and to the letters of reference marked thereon.

The nature of my invention consists in providing a sheave-wheel with amovable axis or axle, rolling upon an extended bearing in a slot orotherwise, in such a manner as to be entirely devoid of friction', theoperation of the same being like that of an ordinary roller, with thisimportant difference and advantage--namely, that in consequence of oneofthe bearings being upon a less diameter than the other, the advanceof-the wheel or roller is a great deal less than that of the door towhich the sheave is attached, thus en abling the wheel to be placedwithin a case or sheave of practicable size.

It is well known that in moving a weight upon an ordinary roller thelatter changes place in reference to the object carried a distance equalto one-half the distance traversed by the load, so that if. the objectcarried is moved four feet the roller will move two feet. This factmakes the application of the ordinary roller to the purposes of asliding sheave altogether impracticable, for where a door is required tomove four feet the roller, being started at the edge of the door, wouldtravel two feet, and thus leave the door without support in one-half itswidth, making it liable to tilt over.v In this invention this difiicultyis entirely overcome, by making the roller travel a very small fractionof the distance traveled by the door.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

In the accompanying' drawings, Figure lis a perspective vit-w of thesheave; Fig. 2, a longitudinal section, and Fig. 3 a transverse section,and the letters of reference refer to the same parts in each ligure.

I provide a wheel, A,v running upon a way or rail, B, in the usualmanner, or upon a smooth surface, as the case may be; but instead ofhaving the axle C of the wheel to revolve in a'iixed socket, I provide aslot, D, and a continuous hearing, E, against and upon which the axle Grevolves, thus acting upon the principle of a roller, and not of awheel, and thus avoiding friction.

To determine `the length of the slot Din any particular case, it is onlynecessary to observe that it is evident that the distance traveled bythe door in one revolution ofthe wheel is equal to the circumference ofthe wheel added to the'circumference of the axle. The distance that thedoor has to move, therefore, divided by the sum of these twocircumfcrences, will determine the number of revolutions of the wheel,and consequently ot' the axle, which number of revolutions, multipliedby the circumference of the axle, determines the distance that thecenter of the axle travels. To this must be added the diameter of theaxle for the two curves at the end of the slot, and the sum will be thelength of the slot at the center of the same. From these premises thefollowing, more concise, rule has been deduced, namely: Multiply thedistance that the door has to travel into the diameter of the axle,divide the product by the sum of the dia-meter both of the wheel andaxle, and add to the quotient the diamete-r ofthe axle. The result willbe the length of the slot at the center thereof. By this rule it will beseen that the slot shown in the drawings, three and threevfourths inchesin length, is sufficient for a door traveling more than three feet,whereas in the case of an ordinary roller the door would not move morethan seven and one-half inches.

I propose to apply this roller in all cases of reciprocal action inwhich wheels or the ordinary rollers have beenor may be applied. Inaddition to the case of sliding doors, shutters, sashes, Src., Iinstance those of printingprcsses, marine railways, and revolvingderricks.

What I claim as my iuvention,and desire to secure byV Letters Patent,is-

The construction and arrangement of a sheave and roller in such `mannerthat when in use the axis of the latter will have imparted to it atranslatory as well as a revolving movement upon the bearings formed inthe body of the sheave, substantially as described.

It. G. I-IATFIELD.

Witnesses J osEPH IRELAND, JAMES E. WARE.

